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Making our own Classes and objects

Making our own Classes and objects. As in real life, we’re now creating classes of objects. a class that defines basic characteristics and functions that apply to all objects of that class Think of a class as a set of functions and variables that belong together to define a particular thing.

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Making our own Classes and objects

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  1. Making our own Classes and objects • As in real life, we’re now creating classes of objects. • a class that defines basic characteristics and functions that apply to all objects of that class • Think of a class as a set of functions and variables that belong together to define a particular thing. • E.g., Savings Account classes would have: • A balance #variable, or attribute • An owner’s name #variable, or attribute • The ability to add money to the account #function, or method • The ability to withdraw money from the account #function, or method • An individual’s Savings Account might have: • $542.79 as a balance • Roderick Feckelbocker as the owner’s name

  2. Creating your own classes class Elephant(object): def __init__(self, name, age, weight, trunkradius, trunklength ): self.name = name self.age = age self.weight = weight self.trunkradius = trunkradius self.trunklength = trunklength • We now have a class of Elephants • Elephants starts with a capital letter • Our Elephants all have names and ages. • __init__: • __init__() is always the constructor in Python • The two __ on both sides of the word init indicate that it is a special name • Constructor is automatically invoked when the an object of this type is created.

  3. Creating an Elephant named Rita: class Elephant(object): def __init__(self, name, age, weight, trunkradius, trunklength ): self.name = name self.age = age self.weight = weight self.trunkradius = trunkradius self.trunklength = trunklength elephant1 = Elephant("Rita",32,6080,10,96) print("The Elephant’s name is " + elephant1.name + "and her age is " + str(elephant1.age)) elephant2 = Elephant("Harold",28,7940,14,100) print("The Elephant’s name is " + elephant2.name + "and his age is " + str(elephant2.age))

  4. Creating an Elephant named Rita: class Elephant(object): def __init__(self, name, age, weight, trunkradius, trunklength): self.name = name self.age = age self.weight = weight self.trunkradius = trunkradius self.trunklength = trunklength # main elephant1 = Elephant("Rita",32,6080,10,96) print("The Elephant’s name is "+elephant1.name+" and her age is "+str(elephant1.age)) print("Her trunk’s volume is" ) ???

  5. Creating an Elephant named Rita: from math import * class Elephant(object): """A virtual pet""" def __init__(self, name, age, weight, trunkradius, trunklength): self.name = name self.age = age self.weight = weight self.trunkradius = trunkradius self.trunklength = trunklength def trunkvol(self): # Notice this is still part of the Elephant class! return(self.trunkradius**2 * pi * self.trunklength) # main elephant1 = Elephant("Rita",32,6080,10,96) print("The Elephant's name is " + elephant1.name + "and her age is " + str(elephant1.age)) print("Her trunk's volume is " + str(elephant1.trunkvol() ))

  6. class Rectangle(object): """ A rectangle is a shape with width and height [DESCRIPTION] width - number [PROPERTIES] height - number """ def __init__(self, width, height): #[CONSTRUCTOR] self.width = width self.height = height def area(self): """ Computes the area of a Rectangle object aRectangle - Rectangle return - number """ return self.width * self.height rectangle1 = Rectangle(10, 10) #[EXAMPLES] rectangle2 = Rectangle(20, 5) print(rectangle1.area()) print(rectangle2.area()) print(Rectangle(6,8).area())

  7. class Rectangle(object): def __init__(self, width, height): #[CONSTRUCTOR] self.width = width self.height = height def area(self): return self.width * self.height def boxvol(self,x): return self.width * self.height * x rectangle1 = Rectangle(10, 10) #[EXAMPLES] rectangle2 = Rectangle(20, 5) print(rectangle1.area()) print(rectangle2.boxvol(2)) print(Rectangle(6,8).area())

  8. class Circle(object): """ A circle is a shape with radius, a circumference, and an area [DESCRIPTION] radius - number [PROPERTIES] circumference – number (2*pi*radius) area – number (pi*radius**2) """ def __init__(self, radius): #[CONSTRUCTOR] self.radius = radius self.area=??? self.circumference=???

  9. Can we include in the class a function that checks if this circle is bigger than another circle? • What type should it return? from math import * class Circle(object): def __init__(self,radius): self.radius = radius self.circumference = self.getcirc() self.area = self.getarea() def getcirc(self): return(self.radius * 2 * pi) def getarea(self): return(self.radius **2 * pi) circ1 = Circle(3) print(circ1.area) print(circ1.circumference)

  10. from math import * class Circle(object): def __init__(self,radius): self.radius = radius self.circumference = self.getcirc() self.area = self.getarea() def getcirc(self): return(self.radius * 2 * pi) def getarea(self): return(self.radius **2 * pi) def isbigger(self, circ2): return(self.area > circ2.area) firstcirc = Circle(3) secondcirc = Circle(4) thirdcirc = Circle(2) print(firstcirc.area) print(firstcirc.isbigger(secondcirc)) print(firstcirc.isbigger(thirdcirc))

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